Laser diode chip

Abstract

To provide a laser diode chip capable of emitting RGB light with one chip and also capable of obtaining high emission efficiency even when a chip is miniaturized.SOLUTION: A laser diode chip has, on an n-type AlxGa1-xN layer (0≤x≤1), AlGaInN laser diode structures (B', G', R') emitting blue light, green light and red light, respectively. These laser diode structures have: an insulating film (703) having at least one rectangular opening (703a) on the n-type AlxGa1-xN layer; a polygonal truncated pyramid-shaped n-type AlyGa1-yN layer (0≤y≤1) (704) on the n-type AlxGa1-xN layer in a portion of the opening; active layers (705-707) each provided along a top surface and a side surface of the n-type AlyGa1-yN layer; p-type AlzGa1-zN layers (0≤z≤1) (708-710) covering each active layer; a p-side electrode (711) on the p-type AlzGa1-zN layers; and an n-side electrode (712) provided on the n-type AlxGa1-xN layer or a rear face thereof.SELECTED DRAWING: Figure 37B

Description

[Technical field]

[0001] The present invention relates to a micro light-emitting diode chip, a manufacturing method for a micro light-emitting diode chip, a substrate for transferring a micro light-emitting diode chip, a manufacturing method for a substrate for transferring a micro light-emitting diode chip, a micro light-emitting diode display, XR (Cross Reality) glasses, and a laser diode chip. [Background technology]

[0002] Micro light-emitting diode (LED) displays can achieve brightness far surpassing that of liquid crystal displays (LCDs) and organic light-emitting diode (OLEDs), and are expected to be applied to XR glasses, large-screen TVs, etc. However, because the manufacturing costs are very high, although commercialization has been realized, the high product price has prevented full-scale adoption.

[0003] In order to reduce costs, it is necessary to miniaturize the chip size to the order of a few micrometers. Therefore, it is necessary to introduce technology to suppress the decrease in light emission efficiency that accompanies miniaturization. The main reason for the decrease in light emission efficiency that accompanies miniaturization is related to the considerable number of defects that occur on the cross section when the chip is separated. Holes and electrons reside most in the active layer, which has the smallest band gap, and emit light by combining with each other there and emitting photons with energy according to the band gap. If there are many defects in the active layer, the proportion of holes and electrons that are captured by the defects and do not contribute to light emission increases. Holes and electrons (especially electrons) can move several micrometers on average before combining with the other carrier (hole) in the active layer. When the width of the active layer becomes the order of several micrometers with the miniaturization of the chip, the proportion of holes and electrons that are captured by defects on the sidewall of the active layer and disappear increases dramatically compared to the proportion of holes and electrons that combine. Therefore, as the chip size becomes smaller, such as several micrometers, the phenomenon of a dramatic decrease in light emission efficiency is observed. If the decrease in light emission efficiency of LEDs can be suppressed even when the chip is miniaturized, the light emission area of ​​the LED required to ensure brightness can be reduced, and material costs can be reduced.

[0004] Regarding the transfer of micro LED chips, there has been remarkable technological development in recent years, such as improvements in transfer speed and transfer yield. However, the reality is that there are still issues that have not been overcome, such as the complexity of the process when transferring three different types of RGB chips onto one pixel, the difficulty of measuring and repairing the characteristics of micro LED chips on the order of a few μm, the difficulty of selecting defective chips due to the difficulty of chip measurement, and the low manufacturing yield due to the inclusion of a small number of defective micro LED chips.

[0005] Recently, a proposal has been announced to simplify the manufacturing process by growing GaN nanorods to form three-color micro LED chips (RGB) on the same substrate, and active research is being conducted (see, for example, Patent Documents 1 and 2 and Non-Patent Document 1). However, it is difficult to ensure the uniformity / reproducibility of the rod height and wavelength when growing GaN nanorods, and there are issues with stable production.

[0006] Furthermore, thanks to vigorous research by various research institutes, the efficiency of InGaN-based red LEDs grown on flat C-face GaN has recently improved, and it is hoped that full-color displays using only GaN-based LEDs without wavelength conversion will be realized (for example, see Non-Patent Document 2).

[0007] However, although expectations are rising, no technology has emerged that can solve all of the above issues at once, such as improving manufacturing yields, and the reality is that low-cost micro LED displays have not yet been realized. For this reason, there is a need for the emergence of technology that simultaneously achieves high manufacturing yields, simplifies the manufacturing process by integrating RGB, etc., and provides measures against efficiency decline due to sidewall damage.

[0008] The present inventor has proposed a method for manufacturing a micro LED display that can realize a micro LED display at low cost (see Patent Documents 3 to 6). In Patent Documents 3 to 5, for example, a micro LED display is manufactured by discharging ink in which a micro LED chip configured to be attracted to a magnetic field more strongly on the p-side electrode side than on the n-side electrode side is dispersed in liquid onto a chip bonding part on the main surface of a substrate, and bonding the p-side electrode side of the micro LED chip to the chip bonding part by applying an external magnetic field from below the substrate. In Patent Document 6, a vertical micro LED chip having multiple p-side electrodes and one n-side electrode on the top and bottom, or a horizontal micro LED chip having multiple p-side electrodes and one n-side electrode on one surface side is bonded to the chip bonding part by a multi-chip transfer method to manufacture a micro LED display. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 5547076 [Patent Document 2] Patent No. 5687731 [Patent Document 3] Patent No. 6694222 [Patent Document 4] Patent No. 6842783 [Patent Document 5] Patent No. 6886213 [Patent Document 6] Patent No. 6803595 [Non-patent literature]

[0010] [Non-Patent Document 1] [Retrieved June 9, 2023], Internet <URL: https: / / shingi.jst.go.jp / pdf / 2018 / 2018_kisoken2_1.pdf > [Non-Patent Document 2] [Retrieved June 9, 2023], Internet <URL: https: / / www.wavefront.co.jp / CAE / MOVPE-database / exp5.html> Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, the problem to be solved by the present invention is to provide a micro light-emitting diode chip capable of emitting RGB light from a single chip and capable of obtaining high light-emitting efficiency even when miniaturized, and a manufacturing method thereof; a micro light-emitting diode chip transfer substrate capable of easily transferring a large number of these micro light-emitting diode chips, and a manufacturing method thereof; a high-performance micro light-emitting diode display using this micro light-emitting diode chip, high-performance XR glasses using this micro light-emitting diode display, and a laser diode chip capable of emitting RGB light from a single chip and capable of obtaining high light-emitting efficiency even when miniaturized. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention provides: at least one blue-emitting AlGaInN-based light-emitting diode structure, at least one green-emitting AlGaInN-based light-emitting diode structure, and at least one red-emitting AlGaInN-based light-emitting diode structure on an n-type GaN layer; The above-mentioned blue-emitting AlGaInN-based light-emitting diode structure, the above-mentioned green-emitting AlGaInN-based light-emitting diode structure, and the above-mentioned red-emitting AlGaInN-based light-emitting diode structure are an insulating film having at least one opening provided on the n-type GaN layer; a polygonal truncated pyramidal GaN layer provided on the n-type GaN layer in the opening of the insulating film; a light emitting layer provided along an upper surface and a side surface of the polygonal truncated pyramidal GaN layer; a p-type GaN layer provided so as to cover the light emitting layer; one or a plurality of p-side electrodes separated from each other provided on an upper surface of the p-type GaN layer; at least one n-side electrode provided on the n-type GaN layer in a portion where the polygonal truncated pyramidal GaN layer is not provided; Let the number of the above blue-emitting AlGaInN-based light-emitting diode structures be N b , the number of the above-mentioned green-emitting AlGaInN-based light-emitting diode structures is N g , the number of the red-emitting AlGaInN-based light-emitting diode structures is N r The number of the p-side electrodes provided on the upper surface of the p-type GaN layer of each of the blue-emitting AlGaInN-based light-emitting diode structure, the green-emitting AlGaInN-based light-emitting diode structure, and the red-emitting AlGaInN-based light-emitting diode structure is set to N p Then, N p ×N b ≧2, N p ×N g ≧2, N p ×N r ≧2.

[0013] The shape of the polygonal pyramid-shaped GaN layer may be various shapes, and is not particularly limited. The polygonal pyramid-shaped GaN layer may be, for example, a hexagonal pyramid, a hexagonal pyramid or an octagonal pyramid that are elongated in one direction, etc. This GaN layer may be undoped or n-type.

[0014] The shape of the opening of the insulating film is selected as necessary, and may be a polygon similar to or similar to the polygonal truncated pyramid GaN layer, or may be a shape other than a polygon, such as a circle. The arrangement of the openings of the insulating film is also selected as necessary. The insulating film is selected as necessary, and examples of the insulating film that can be used include oxide films (SiO2 film, etc.), nitride films (Si3N4 film, etc.), oxynitride films (SiON film, etc.), and titanium oxide films (TiO2 film, etc.). Preferably, a part of the n-type GaN layer is formed by lateral growth, and the opening of the insulating film is formed on the n-type GaN layer in the part formed by the lateral growth. In this way, the threading dislocation density of the polygonal truncated pyramid GaN layer provided on the n-type GaN layer in the opening of the insulating film can be significantly reduced, and thereby the decrease in luminous efficiency due to non-radiative recombination in the threading dislocation part propagating from the polygonal truncated pyramid GaN layer to the light emitting layer and the leakage current due to the threading dislocation can be suppressed.

[0015] For example, the thickness of the p-type GaN layer above the top surface of the truncated pyramidal GaN layer may be selected to be smaller than the thickness of the p-type GaN layer above the side surface of the truncated pyramidal GaN layer, so that light is emitted mainly from the light emitting layer on the top surface of the truncated pyramidal GaN layer, or conversely, the thickness of the p-type GaN layer above the side surface of the truncated pyramidal GaN layer may be selected to be smaller than the thickness of the p-type GaN layer above the top surface of the truncated pyramidal GaN layer, so that light is emitted mainly from the light emitting layer on the side surface of the truncated pyramidal GaN layer.

[0016] The p-side electrode may be at least partially transparent, and light from the light-emitting layer may be extracted to the outside through this transparent portion, or it may be made of a material containing a highly reflective metal layer such as Ag, and light from the light-emitting layer may be extracted to the outside mainly from the n-side (for example, in a flip-chip mounting where the p-side electrode (p-type layer) is on the mounting substrate side). The n-side electrode is provided on the n-type GaN layer in a portion where the polygonal truncated pyramidal GaN layer is not provided, and is typically provided so as to contact the n-type GaN layer through an opening provided in an insulating film provided on the n-type GaN layer.

[0017] The blue-emitting AlGaInN-based light-emitting diode structure, green-emitting AlGaInN-based light-emitting diode structure, and red-emitting AlGaInN-based light-emitting diode structure typically have an InGaN-based light-emitting layer, and by controlling the growth conditions of the light-emitting layer, any of blue emission (e.g., wavelength 440 nm to 470 nm), green emission (e.g., wavelength 515 nm to 545 nm), and red emission (e.g., wavelength 605 nm to 655 nm) is possible.

[0018] The chip size of the micro light-emitting diode chip is selected as needed, but is generally 20 μm×20 μm or less, typically 10 μm×10 μm or less, most typically 5 μm×5 μm or less, and typically 0.5 μm×0.5 μm or more. The thickness of the micro light-emitting diode chip is also selected as needed, but is typically 1 μm or more and 6 μm or less. The micro light-emitting diode chip is preferably a chip obtained by performing crystal growth of a semiconductor layer constituting a light-emitting diode structure on a substrate, and then separating the substrate from the semiconductor layer. The overall shape of the micro light-emitting diode chip is selected as needed, and is not particularly limited, but is typically a square or a rectangle. The side surface of the micro light-emitting diode chip is formed so that the upper surface portion of the GaN layer of the polygonal truncated pyramidal GaN layer, which is a light-emitting layer provided along the upper surface and side surface, is not exposed to the side surface. In this way, even if defects are present on the side surface formed by chipping when the semiconductor layer constituting the light-emitting diode structure is separated by dry etching such as RIE after crystal growth of the semiconductor layer on the substrate, the defects have almost no effect on the light emission because they are located sufficiently far away from the light-emitting layer on the upper surface of the truncated polygonal pyramidal GaN layer where light emission mainly occurs. When one micro light-emitting diode chip has multiple truncated polygonal pyramidal GaN layers, the side surface of the micro light-emitting diode chip is formed such that the upper surface portion of the GaN layer of the light-emitting layer provided along the upper surface and side surface of at least one or more truncated polygonal pyramidal GaN layers is not exposed on the side surface.

[0019] In this micro light-emitting diode chip, the number N of blue-emitting AlGaInN-based light-emitting diode structures isb , the number of green-emitting AlGaInN-based light-emitting diode structures N g , the number of red-emitting AlGaInN-based light-emitting diode structures N r , the number N of p-side electrodes provided on the upper surface of the p-type GaN layer of each of the blue-emitting AlGaInN-based light-emitting diode structure, the green-emitting AlGaInN-based light-emitting diode structure, and the red-emitting AlGaInN-based light-emitting diode structure. p is N p ×N b ≧2, N p ×N g ≧2, N p ×N r As long as it satisfies ≧2, any selection may be made. For example, N p ×N b ≧3, N p ×N g ≧3, N p ×N r ≧3. For example, N p = 1, then N b ≧2, N g ≧2, N r ≧2, so for example, N b , N g , N r can be 2, 3 or 4. b =1, N g =1, N r If =1, then N p ≧2.

[0020] The present invention also provides forming a first insulating film having a first opening in a portion where a first AlGaInN-based light emitting diode structure selected from a blue-emitting AlGaInN-based light emitting diode structure, a green-emitting AlGaInN-based light emitting diode structure, and a red-emitting AlGaInN-based light emitting diode structure is to be formed on an n-type GaN layer provided on a substrate; forming the first AlGaInN-based light-emitting diode structure by successively growing a polygonal truncated pyramidal GaN layer, a light-emitting layer and a p-type GaN layer on the n-type GaN layer in the first opening of the first insulating film; forming a second insulating film so as to cover the first AlGaInN based light emitting diode structure; forming a second opening in a portion of the first insulating film where a second AlGaInN-based light-emitting diode structure other than the first AlGaInN-based light-emitting diode structure is to be formed, the second AlGaInN-based light-emitting diode structure being selected from a blue-emitting AlGaInN-based light-emitting diode structure, a green-emitting AlGaInN-based light-emitting diode structure, and a red-emitting AlGaInN-based light-emitting diode structure; forming the second AlGaInN-based light-emitting diode structure by successively growing a polygonal truncated pyramidal GaN layer, a light-emitting layer and a p-type GaN layer on the n-type GaN layer in the second opening of the first insulating film; forming a third insulating film so as to cover the second AlGaInN based light emitting diode structure; forming a third opening in a portion of the first insulating film where a third AlGaInN-based light-emitting diode structure other than the first AlGaInN-based light-emitting diode structure and the second AlGaInN-based light-emitting diode structure is to be formed, among the blue-emitting AlGaInN-based light-emitting diode structure, the green-emitting AlGaInN-based light-emitting diode structure, and the red-emitting AlGaInN-based light-emitting diode structure; forming the third AlGaInN-based light-emitting diode structure by successively growing a polygonal truncated pyramidal GaN layer, a light-emitting layer and a p-type GaN layer on the n-type GaN layer in the third opening of the first insulating film; forming a fourth insulating film so as to cover the third AlGaInN based light emitting diode structure; forming a first contact hole, a second contact hole and a third contact hole in the second insulating film covering the first AlGaInN-based light-emitting diode structure, the third insulating film covering the second AlGaInN-based light-emitting diode structure and the fourth insulating film covering the third AlGaInN-based light-emitting diode structure, respectively; forming a p-side electrode in contact with the p-type GaN layer through the first contact hole, the second contact hole, and the third contact hole; forming a fourth contact hole in a portion of the first insulating film other than the polygonal truncated pyramid-shaped semiconductor layer; forming an n-side electrode in contact with the n-type GaN layer through the fourth contact hole; forming a separation groove reaching the substrate so as to define a chip region including at least one of the first AlGaInN-based light-emitting diode structure, at least one of the second AlGaInN-based light-emitting diode structure, at least one of the third AlGaInN-based light-emitting diode structure, and at least one of the n-side electrodes; separating the substrate from the n-type GaN layer; The present invention relates to a method for manufacturing a micro light-emitting diode chip having the above structure.

[0021] The above-mentioned micro light-emitting diode chip can be manufactured by this manufacturing method for the micro light-emitting diode chip.

[0022] The substrate is not particularly limited as long as it allows the growth of an AlGaInN-based semiconductor (especially C-plane growth), and examples thereof include a sapphire substrate and a Si substrate. As the first to fourth insulating films, insulating films similar to those in the micro light-emitting diode chip described above can be used. In the invention of the manufacturing method for the micro light-emitting diode chip, the matters described in relation to the invention of the micro light-emitting diode chip described above apply except for the above, unless they are contrary to the nature of the invention.

[0023] The present invention also provides forming a fifth insulating film having fourth openings in a portion for forming a blue light emitting AlGaInN based light emitting diode structure, a portion for forming a green light emitting AlGaInN based light emitting diode structure, and a portion for forming a red light emitting AlGaInN based light emitting diode structure on an n-type GaN layer provided on a substrate; growing a polygonal truncated pyramidal GaN layer on the n-type GaN layer in the fourth opening of the fifth insulating film; growing a first light emitting layer for the blue light emitting AlGaInN based light emitting diode structure along an upper surface and a side surface of the polygonal truncated pyramidal GaN layer; forming a sixth insulating film so as to cover the first light emitting layer in a portion other than a portion where the green light emitting AlGaInN based light emitting diode structure is to be formed and a portion where the red light emitting AlGaInN based light emitting diode structure is to be formed; growing a second light emitting layer for a green light emitting AlGaInN based light emitting diode structure on the first light emitting layer in a portion for forming the green light emitting AlGaInN based light emitting diode structure and a portion for forming the red light emitting AlGaInN based light emitting diode structure; forming a seventh insulating film so as to cover the second light emitting layer except for a portion where the red light emitting AlGaInN based light emitting diode structure is to be formed; growing a third light emitting layer for the red light emitting AlGaInN based light emitting diode structure in a portion where the red light emitting AlGaInN based light emitting diode structure is to be formed; forming an eighth insulating film so as to cover the third light-emitting layer; forming a fifth contact hole, a sixth contact hole and a seventh contact hole in the sixth insulating film covering the blue light emitting AlGaInN based light emitting diode structure, the seventh insulating film covering the green light emitting AlGaInN based light emitting diode structure and the eighth insulating film covering the red light emitting AlGaInN based light emitting diode structure, respectively; forming p-side electrodes in contact with the p-type GaN layer through the fifth contact hole, the sixth contact hole, and the seventh contact hole; forming an eighth contact hole in a portion of the first insulating film other than the polygonal truncated pyramid-shaped semiconductor layer; forming an n-side electrode in contact with the n-type GaN layer through the eighth contact hole; forming a separation groove reaching the substrate so as to define a chip region including at least one of the blue-emitting AlGaInN-based light-emitting diode structures, at least one of the green-emitting AlGaInN-based light-emitting diode structures, at least one of the red-emitting AlGaInN-based light-emitting diode structures, and at least one of the n-side electrodes; separating the substrate from the n-type GaN layer; The present invention relates to a method for manufacturing a micro light-emitting diode chip having the above structure.

[0024] The above-mentioned micro light-emitting diode chip can be manufactured by this manufacturing method for the micro light-emitting diode chip.

[0025] The substrate and the fifth to eighth insulating films are the same as the substrate and the first to fourth insulating films in the manufacturing method for the micro light-emitting diode chip described above. In the invention of the manufacturing method for the micro light-emitting diode chip, the matters described in relation to the invention of the micro light-emitting diode chip described above apply except for the above, unless they are contrary to the nature of the invention.

[0026] The present invention also provides a chip region including at least one blue-emitting AlGaInN-based light-emitting diode structure, at least one green-emitting AlGaInN-based light-emitting diode structure, and at least one red-emitting AlGaInN-based light-emitting diode structure is arranged in a two-dimensional array on an n-type GaN layer provided on a substrate; The above-mentioned blue-emitting AlGaInN-based light-emitting diode structure, the above-mentioned green-emitting AlGaInN-based light-emitting diode structure, and the above-mentioned red-emitting AlGaInN-based light-emitting diode structure are an insulating film having at least one opening provided on the n-type GaN layer; a polygonal truncated pyramidal GaN layer provided on the n-type GaN layer in the opening of the insulating film; a light emitting layer provided along an upper surface and a side surface of the polygonal truncated pyramidal GaN layer; a p-type GaN layer provided so as to cover the light emitting layer; one or a plurality of p-side electrodes separated from each other provided on an upper surface of the p-type GaN layer; at least one n-side electrode provided on the n-type GaN layer in a portion where the polygonal truncated pyramidal GaN layer is not provided; Let the number of the above blue-emitting AlGaInN-based light-emitting diode structures be N b , the number of the above-mentioned green-emitting AlGaInN-based light-emitting diode structures is N g , the number of the red-emitting AlGaInN-based light-emitting diode structures is N r The number of the p-side electrodes provided on the upper surface of the p-type GaN layer of each of the blue-emitting AlGaInN-based light-emitting diode structure, the green-emitting AlGaInN-based light-emitting diode structure, and the red-emitting AlGaInN-based light-emitting diode structure is set to N p Then, N p ×N b ≧2, N p ×N g ≧2, N p ×N r ≧2, The chip region is a substrate for transferring micro light-emitting diode chips, which is defined by a separation groove that separates the n-type GaN layer.

[0027] The present invention also provides forming a first insulating film having a first opening in a portion where a first AlGaInN-based light emitting diode structure selected from a blue-emitting AlGaInN-based light emitting diode structure, a green-emitting AlGaInN-based light emitting diode structure, and a red-emitting AlGaInN-based light emitting diode structure is to be formed on an n-type GaN layer provided on a substrate; forming the first AlGaInN-based light-emitting diode structure by successively growing a polygonal truncated pyramidal GaN layer, a light-emitting layer and a p-type GaN layer on the n-type GaN layer in the first opening of the first insulating film; forming a second insulating film so as to cover the first AlGaInN based light emitting diode structure; forming a second opening in a portion of the first insulating film where a second AlGaInN-based light-emitting diode structure other than the first AlGaInN-based light-emitting diode structure is to be formed, the second AlGaInN-based light-emitting diode structure being selected from a blue-emitting AlGaInN-based light-emitting diode structure, a green-emitting AlGaInN-based light-emitting diode structure, and a red-emitting AlGaInN-based light-emitting diode structure; forming the second AlGaInN-based light-emitting diode structure by successively growing a polygonal truncated pyramidal GaN layer, a light-emitting layer and a p-type GaN layer on the n-type GaN layer in the second opening of the first insulating film; forming a third insulating film so as to cover the second AlGaInN based light emitting diode structure; forming a third opening in a portion of the first insulating film where a third AlGaInN-based light-emitting diode structure other than the first AlGaInN-based light-emitting diode structure and the second AlGaInN-based light-emitting diode structure is to be formed, among the blue-emitting AlGaInN-based light-emitting diode structure, the green-emitting AlGaInN-based light-emitting diode structure, and the red-emitting AlGaInN-based light-emitting diode structure; forming the third AlGaInN-based light-emitting diode structure by successively growing a polygonal truncated pyramidal GaN layer, a light-emitting layer and a p-type GaN layer on the n-type GaN layer in the third opening of the first insulating film; forming a fourth insulating film so as to cover the third AlGaInN based light emitting diode structure; forming a first contact hole, a second contact hole and a third contact hole in the second insulating film covering the first AlGaInN-based light-emitting diode structure, the third insulating film covering the second AlGaInN-based light-emitting diode structure and the fourth insulating film covering the third AlGaInN-based light-emitting diode structure, respectively; forming a p-side electrode in contact with the p-type GaN layer through the first contact hole, the second contact hole, and the third contact hole; forming a fourth contact hole in a portion of the first insulating film other than the polygonal truncated pyramid-shaped semiconductor layer; forming an n-side electrode in contact with the n-type GaN layer through the fourth contact hole; forming a separation groove separating the n-type GaN layer so as to define a chip region including at least one of the first AlGaInN-based light-emitting diode structure, at least one of the second AlGaInN-based light-emitting diode structure, at least one of the third AlGaInN-based light-emitting diode structure, and at least one of the n-side electrodes; The present invention relates to a method for manufacturing a substrate for transferring micro light-emitting diode chips.

[0028] By this method for producing a micro light-emitting diode chip transfer substrate, the above-mentioned micro light-emitting diode chip transfer substrate can be produced.

[0029] The present invention also provides forming a fifth insulating film having fourth openings in a portion for forming a blue light emitting AlGaInN based light emitting diode structure, a portion for forming a green light emitting AlGaInN based light emitting diode structure, and a portion for forming a red light emitting AlGaInN based light emitting diode structure on an n-type GaN layer provided on a substrate; growing a polygonal truncated pyramidal GaN layer on the n-type GaN layer in the fourth opening of the fifth insulating film; growing a first light emitting layer for the blue light emitting AlGaInN based light emitting diode structure along an upper surface and a side surface of the polygonal truncated pyramidal GaN layer; forming a sixth insulating film so as to cover the first light emitting layer in a portion other than a portion where the green light emitting AlGaInN based light emitting diode structure is to be formed and a portion where the red light emitting AlGaInN based light emitting diode structure is to be formed; growing a second light emitting layer for a green light emitting AlGaInN based light emitting diode structure on the first light emitting layer in a portion for forming the green light emitting AlGaInN based light emitting diode structure and a portion for forming the red light emitting AlGaInN based light emitting diode structure; forming a seventh insulating film so as to cover the second light emitting layer except for a portion where the red light emitting AlGaInN based light emitting diode structure is to be formed; growing a third light emitting layer for the red light emitting AlGaInN based light emitting diode structure in a portion where the red light emitting AlGaInN based light emitting diode structure is to be formed; forming an eighth insulating film so as to cover the third light-emitting layer; forming a fifth contact hole, a sixth contact hole and a seventh contact hole in the sixth insulating film covering the blue light emitting AlGaInN based light emitting diode structure, the seventh insulating film covering the green light emitting AlGaInN based light emitting diode structure and the eighth insulating film covering the red light emitting AlGaInN based light emitting diode structure, respectively; forming p-side electrodes in contact with the p-type GaN layer through the fifth contact hole, the sixth contact hole, and the seventh contact hole; forming an eighth contact hole in a portion of the first insulating film other than the polygonal truncated pyramid-shaped semiconductor layer; forming an n-side electrode in contact with the n-type GaN layer through the eighth contact hole; forming a separation groove separating the n-type GaN layer so as to define a chip region including at least one of the blue-emitting AlGaInN-based light-emitting diode structures, at least one of the green-emitting AlGaInN-based light-emitting diode structures, at least one of the red-emitting AlGaInN-based light-emitting diode structures, and at least one of the n-side electrodes; The present invention relates to a method for manufacturing a substrate for transferring micro light-emitting diode chips.

[0030] By this method for producing a micro light-emitting diode chip transfer substrate, the above-mentioned micro light-emitting diode chip transfer substrate can be produced.

[0031] The present invention also provides a display unit in which a plurality of micro light-emitting diode chips are mounted in a two-dimensional array; a drive circuit section in which a plurality of drive circuits that can be controlled and driven independently of each other are arranged in a two-dimensional array; a wiring circuit for wiring the display unit and the drive circuit unit, The micro light emitting diode chip is at least one blue-emitting AlGaInN-based light-emitting diode structure, at least one green-emitting AlGaInN-based light-emitting diode structure, and at least one red-emitting AlGaInN-based light-emitting diode structure on an n-type GaN layer; The above-mentioned blue-emitting AlGaInN-based light-emitting diode structure, the above-mentioned green-emitting AlGaInN-based light-emitting diode structure, and the above-mentioned red-emitting AlGaInN-based light-emitting diode structure are an insulating film having at least one opening provided on the n-type GaN layer; a polygonal truncated pyramidal GaN layer provided on the n-type GaN layer in the opening of the insulating film; a light emitting layer provided along an upper surface and a side surface of the polygonal truncated pyramidal GaN layer; a p-type GaN layer provided so as to cover the light emitting layer; one or a plurality of p-side electrodes separated from each other provided on an upper surface of the p-type GaN layer; at least one n-side electrode provided on the n-type GaN layer in a portion where the polygonal truncated pyramidal GaN layer is not provided; Let the number of the above blue-emitting AlGaInN-based light-emitting diode structures be N b , the number of the above-mentioned green-emitting AlGaInN-based light-emitting diode structures is N g , the number of the red-emitting AlGaInN-based light-emitting diode structures is N r The number of the p-side electrodes provided on the upper surface of the p-type GaN layer of each of the blue-emitting AlGaInN-based light-emitting diode structure, the green-emitting AlGaInN-based light-emitting diode structure, and the red-emitting AlGaInN-based light-emitting diode structure is set to N p Then, N p ×N b ≧2, N p ×Ng ≧2, N p ×N r ≧2. The micro light-emitting diode display is a micro light-emitting diode chip.

[0032] This micro light-emitting diode display can be used as a color display because the micro light-emitting diode chip can emit light in three colors, red, green, and blue (RGB). This micro light-emitting diode display may be any of a passive matrix driving method, an active matrix driving method, a pulse width modulation (PWM) driving method, and the like. In a color display using a PWM driving method, for example, the micro light-emitting diode chip may be transferred onto an IC substrate having a built-in PWM driving circuit. In a typical example of this micro light-emitting diode display, a plurality of p-side electrodes are provided separately for each of the blue-emitting AlGaInN-based light-emitting diode structure, the green-emitting AlGaInN-based light-emitting diode structure, and the red-emitting AlGaInN-based light-emitting diode structure, and at least one n-side electrode is provided, and each micro light-emitting diode chip is electrically connected to each of a plurality of branch wirings branched from a first trunk wiring connected to the driving circuit of the driving circuit section via the wiring of the wiring circuit, and the n-side electrode is electrically connected to each of the second trunk wiring connected to the driving circuit of the driving circuit section via the wiring of the wiring circuit.

[0033] The present invention also provides A display is provided. The above display is a display unit in which a plurality of micro light-emitting diode chips are mounted in a two-dimensional array; A drive circuit board on which a plurality of drive circuits that can be controlled and driven independently of each other are arranged in a two-dimensional array; a flexible printed circuit for wiring the display unit and the drive circuit board; The micro light emitting diode chip is at least one blue-emitting AlGaInN-based light-emitting diode structure, at least one green-emitting AlGaInN-based light-emitting diode structure, and at least one red-emitting AlGaInN-based light-emitting diode structure on an n-type GaN layer; The above-mentioned blue-emitting AlGaInN-based light-emitting diode structure, the above-mentioned green-emitting AlGaInN-based light-emitting diode structure, and the above-mentioned red-emitting AlGaInN-based light-emitting diode structure are an insulating film having at least one opening provided on the n-type GaN layer; a polygonal truncated pyramidal GaN layer provided on the n-type GaN layer in the opening of the insulating film; a light emitting layer provided along an upper surface and a side surface of the polygonal truncated pyramidal GaN layer; a p-type GaN layer provided so as to cover the light emitting layer; one or a plurality of p-side electrodes separated from each other provided on an upper surface of the p-type GaN layer; at least one n-side electrode provided on the n-type GaN layer in a portion where the polygonal truncated pyramidal GaN layer is not provided; Let the number of the above blue-emitting AlGaInN-based light-emitting diode structures be N b , the number of the above-mentioned green-emitting AlGaInN-based light-emitting diode structures is N g , the number of the red-emitting AlGaInN-based light-emitting diode structures is N r The number of the p-side electrodes provided on the upper surface of the p-type GaN layer of each of the blue-emitting AlGaInN-based light-emitting diode structure, the green-emitting AlGaInN-based light-emitting diode structure, and the red-emitting AlGaInN-based light-emitting diode structure is set to N p Then, N p ×N b ≧2, N p ×N g ≧2, N p ×N r ≧2, The display unit is attached to the inside surface of the windshield unit, The drive circuit board is attached to the ear hook of the frame, The flexible printed circuit is mounted in a frame of the XR glasses.

[0034] XR (Cross Reality) glasses are a general term for glasses that use technologies such as VR (Virtual Reality), AR (Augmented Reality), MR (Mixed Reality), and SR (Substitutional Reality), as well as combinations of these technologies (e.g., a technology that combines VR and AR), and intermediate technologies between these technologies (e.g., a technology that is positioned between AR and MR). They are image display devices that create a space that provides a simulated experience by combining the real and virtual worlds. VR is a technology that allows you to experience the virtual world as if it were the real world, AR is a technology that projects the virtual world onto the real space, MR is a technology that combines the real space and the virtual space, and SR is a technology that overlays past images onto the real space, making it appear as if past events are happening right in front of you.

[0035] In this XR glass, in a typical example, a plurality of p-side electrodes are provided separately from each other for each of the blue-emitting AlGaInN-based light-emitting diode structure, the green-emitting AlGaInN-based light-emitting diode structure, and the red-emitting AlGaInN-based light-emitting diode structure, and at least one n-side electrode is provided. In each micro light-emitting diode chip, the p-side electrode is electrically connected to each of a plurality of branch wirings branched from a first main wiring connected to the drive circuit of the drive circuit section via wiring of the wiring circuit, and the n-side electrode is electrically connected to each of the second main wirings connected to the drive circuit of the drive circuit section via wiring of the wiring circuit.

[0036] The present invention also provides n-type Al x Ga 1-xat least one blue-emitting AlGaInN-based laser diode structure, at least one green-emitting AlGaInN-based laser diode structure, and at least one red-emitting AlGaInN-based laser diode structure on an N layer (0≦x≦1); The above-mentioned blue-emitting AlGaInN-based laser diode structure, the above-mentioned green-emitting AlGaInN-based laser diode structure, and the above-mentioned red-emitting AlGaInN-based laser diode structure are The above n-type Al x Ga 1-x an insulating film having at least one rectangular opening provided on the N layer; The n-type Al in the opening of the insulating film x Ga 1-x Polygonal truncated pyramidal n-type Al on the N layer y Ga 1-y N layers (0≦y≦1), The above polygonal truncated pyramid-shaped n-type Al y Ga 1-y an active layer provided along the top and side surfaces of the N layer; A p-type Al layer is provided to cover the active layer. z Ga 1-z N layers (0≦z≦1), The above p-type Al z Ga 1-z a p-side electrode provided on the top surface of the N layer; The above polygonal truncated pyramid-shaped n-type Al y Ga 1-y The n-type Al in the portion where the N layer is not provided x Ga 1-x n-type Al on or above the N layer x Ga 1-x The laser diode chip has an n-side electrode provided on the back surface of the N layer.

[0037] The laser diode chip preferably has a double heterostructure in which an active layer is sandwiched between an optical waveguide layer and a cladding layer. In this case, n-type Al y Ga 1-y The N layer includes an n-type cladding layer and an n-type optical waveguide layer, and a p-type Al z Ga 1-zThe N layer includes a p-type optical waveguide layer and a p-type cladding layer. The blue-emitting AlGaInN-based laser diode structure, the green-emitting AlGaInN-based laser diode structure, and the red-emitting AlGaInN-based laser diode structure are configured to have a horizontal cavity, and an anti-reflection film and a reflection film are provided on one end face and the other end face of the horizontal cavity, respectively. In this laser diode chip invention, the description related to the above micro light-emitting diode chip is valid unless it is contrary to its nature.

[0038] This laser diode chip can be used, for example, as a light source for retinal projection type AR glasses, or a laser display combined with a GLV (Grating Light Valve) can be used as a display for XR glasses. Effect of the Invention

[0039] According to this invention, the micro light-emitting diode chip has a blue-emitting AlGaInN-based light-emitting diode structure, a green-emitting AlGaInN-based light-emitting diode structure, and a red-emitting AlGaInN-based light-emitting diode structure on an n-type GaN layer, so that one chip can emit blue, green, and red light. Moreover, in each light-emitting diode structure, a light-emitting layer is provided along the top and side surfaces of the polygonal truncated GaN layer. Therefore, even if defects are present on the side surfaces of the micro light-emitting diode chip due to dry etching or the like, the effect of these defects is hardly felt on the light emission. Therefore, even when the micro light-emitting diode chip is miniaturized, high light-emitting efficiency can be obtained, and further, since the structure is simple, the chip can be easily manufactured.

[0040] According to this invention, it is possible to independently optimize the crystal growth parameters (growth pressure, growth rate, temperature, flow rate, supply ratio of raw materials, etc.) for each emission wavelength, and it is possible to grow under crystal growth conditions that realize the maximum performance (luminous efficiency) for each emission wavelength. Since there are multiple crystal growth parameters, the manufacturing method of the present invention, which can independently optimize each wavelength, is extremely advantageous in improving luminous efficiency.

[0041] This high-performance micro light-emitting diode chip can be used to realize a high-performance micro LED display, and this micro LED display can be used to realize high-performance XR glasses. In addition, by using a micro light-emitting diode chip transfer substrate having a blue light-emitting AlGaInN-based light-emitting diode structure, a green light-emitting AlGaInN-based light-emitting diode structure, and a red light-emitting AlGaInN-based light-emitting diode structure on an n-type GaN layer in each chip region, for example, millions to tens of millions of micro light-emitting diode chips can be transferred at once to a mounting substrate, and a large-area or high-density micro LED display can be easily manufactured.

[0042] According to this invention, one chip can emit blue, green and red light, and has multiple electrodes or light-emitting diode structures for each emission wavelength, which can be controlled independently. Therefore, even if inspection of individual chips (total inspection) is omitted and millions to tens of millions of micro light-emitting diode chips are transferred and assembled at once, pixels can be repaired by isolating the defective part by disconnecting the wiring, thereby ensuring a high manufacturing yield of micro LED displays.

[0043] According to the present invention, the laser diode chip is made of n-type Al x Ga 1-x Since a blue-emitting AlGaInN-based laser diode structure, a green-emitting AlGaInN-based laser diode structure, and a red-emitting AlGaInN-based laser diode structure are provided on the N layer, blue, green, and red light can be emitted from a single chip. Moreover, each laser diode structure has a polygonal truncated n-type Al y Ga 1-ySince the light-emitting layer is provided along the top and side surfaces of the N layer, even if there are defects on the side surfaces of the laser diode chip caused by dry etching or the like, the effect on light emission is minimal. As a result, high light-emitting efficiency can be obtained even when miniaturized, and the simple structure allows for easy manufacture. [Brief description of the drawings]

[0044] [Figure 1A] 1 is a perspective view showing a micro LED chip according to a first embodiment of the present invention; FIG. [Figure 1B] 1 is a cross-sectional view showing a micro LED chip according to a first embodiment of the present invention; [Figure 1C] 1 is a cross-sectional view showing a micro LED chip according to a first embodiment of the present invention; [Figure 2A] FIG. 2 is a plan view for explaining an example of a manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 2B] 1A to 1C are cross-sectional views for explaining an example of a manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Diagram 3] 1A to 1C are cross-sectional views for explaining an example of a manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 4] 1A to 1C are cross-sectional views for explaining an example of a manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Diagram 5] 1A to 1C are cross-sectional views for explaining an example of a manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 6] 1A to 1C are cross-sectional views for explaining an example of a manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 7] 1A to 1C are cross-sectional views for explaining an example of a manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 8] 1A to 1C are cross-sectional views for explaining an example of a manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 9] 1A to 1C are cross-sectional views for explaining an example of a manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 10A] 1A to 1C are cross-sectional views for explaining an example of a manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 10B] 1A to 1C are cross-sectional views for explaining an example of a manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 11A] 1A to 1C are cross-sectional views for explaining an example of a manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 11B] 1A to 1C are cross-sectional views for explaining an example of a manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 12] 1A to 1C are cross-sectional views for explaining an example of a manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 13] 1A to 1C are cross-sectional views for explaining an example of a manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 14] 1A to 1C are cross-sectional views for explaining an example of a manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 15A] FIG. 4 is a plan view for explaining another example of the manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 15B] 5A to 5C are cross-sectional views for explaining another example of the manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 16] 5A to 5C are cross-sectional views for explaining another example of the manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 17] 5A to 5C are cross-sectional views for explaining another example of the manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 18] 5A to 5C are cross-sectional views for explaining another example of the manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 19]5A to 5C are cross-sectional views for explaining another example of the manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 20] 5A to 5C are cross-sectional views for explaining another example of the manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 21] 5A to 5C are cross-sectional views for explaining another example of the manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 22] 5A to 5C are cross-sectional views for explaining another example of the manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 23] 5A to 5C are cross-sectional views for explaining another example of the manufacturing method of the micro LED chip according to the first embodiment of the present invention. [Figure 24] FIG. 11 is a cross-sectional view showing a micro LED chip transfer substrate according to a second embodiment of the present invention. [Figure 25A] 10A to 10C are cross-sectional views for explaining a manufacturing method of a micro LED chip transfer substrate according to a second embodiment of the present invention. [Figure 25B] 10A to 10C are cross-sectional views for explaining a manufacturing method of a micro LED chip transfer substrate according to a second embodiment of the present invention. [Figure 26A] FIG. 11 is a perspective view showing a micro LED chip according to a third embodiment of the present invention. [Figure 26B] FIG. 11 is a cross-sectional view showing a micro LED chip according to a third embodiment of the present invention. [Figure 26C] FIG. 11 is a cross-sectional view showing a micro LED chip according to a third embodiment of the present invention. [Figure 27A] FIG. 11 is a plan view for explaining a manufacturing method of the micro LED chip according to the third embodiment of the present invention. [Figure 27B] 11A to 11C are cross-sectional views for explaining a manufacturing method of a micro LED chip according to a third embodiment of the present invention. [Figure 28A] FIG. 11 is a plan view for explaining a manufacturing method of the micro LED chip according to the third embodiment of the present invention. [Figure 28B]11A to 11C are cross-sectional views for explaining a manufacturing method of a micro LED chip according to a third embodiment of the present invention. [Figure 29] FIG. 10 is a cross-sectional view showing a micro LED chip transfer substrate according to a fourth embodiment of the present invention. [Diagram 30] FIG. 13 is a perspective view showing XR glasses according to a fifth embodiment of the present invention. [Diagram 31] FIG. 13 is a plan view showing a display unit 300, a flexible printed circuit 400 and a printed circuit board 500 of XR glasses according to a fifth embodiment of the present invention. [Figure 32A] FIG. 13 is a plan view showing a display unit 300 of XR glasses according to a fifth embodiment of the present invention. [Figure 32B] FIG. 13 is a cross-sectional view showing a display unit 300 of XR glasses according to a fifth embodiment of the present invention. [Figure 32C] FIG. 13 is a cross-sectional view showing a display unit 300 of XR glasses according to a fifth embodiment of the present invention. [Diagram 33] FIG. 13 is a perspective view showing XR glasses according to a sixth embodiment of the present invention. [Diagram 34] FIG. 13 is an exploded view of a light engine 600 of XR glasses according to a sixth embodiment of the present invention. [Figure 35A] FIG. 13 is a plan view showing an LED array unit 610 of XR glasses according to a sixth embodiment of the present invention. [Figure 35B] FIG. 13 is a cross-sectional view showing an LED array section 610 of XR glasses according to a sixth embodiment of the present invention. [Figure 35C] FIG. 13 is a cross-sectional view showing an LED array section 610 of XR glasses according to a sixth embodiment of the present invention. [Diagram 36] FIG. 13 is a cross-sectional view showing the configuration of a light engine 600 of XR glasses according to a seventh embodiment of the present invention. [Figure 37A] FIG. 13 is a plan view showing an LD chip according to an eighth embodiment of the present invention. [Figure 37B] FIG. 13 is a cross-sectional view showing an LD chip according to an eighth embodiment of the present invention. [Figure 38A] 13A to 13C are cross-sectional views for explaining a manufacturing method of an LD chip according to an eighth embodiment of the present invention. [Figure 38B] 13A to 13C are cross-sectional views for explaining a manufacturing method of an LD chip according to an eighth embodiment of the present invention. [Figure 38C] 13A to 13C are cross-sectional views for explaining a manufacturing method of an LD chip according to an eighth embodiment of the present invention. [Figure 38D] 13A to 13C are cross-sectional views for explaining a manufacturing method of an LD chip according to an eighth embodiment of the present invention. [Figure 38E] 13A to 13C are cross-sectional views for explaining a manufacturing method of an LD chip according to an eighth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] Hereinafter, modes for carrying out the invention (hereinafter referred to as "embodiments") will be described.

[0046] First Embodiment [Micro LED chip] 1A, 1B and 1C show a micro LED chip 10 according to a first embodiment, in which 1A is a perspective view, 1B is a cross-sectional view taken along line BB in 1A, and 1C is a cross-sectional view taken along line CC in 1A. As shown in 1A, 1B and 1C, the micro LED chip 10 has a square or rectangular shape and includes a blue-emitting AlGaInN-based LED structure B, a green-emitting AlGaInN-based LED structure G and a red-emitting AlGaInN-based LED structure R. In the micro LED chip 10, an insulating film 12 is provided on an n-type GaN layer 11. As already mentioned, the insulating film 12 is a SiO2 film or the like. The thickness of the insulating film 12 is selected as required, and is, for example, 10 to 30 nm. The n-type GaN layer 11 is generally grown on a sapphire substrate or a Si substrate via a low-temperature buffer layer, but usually has a large number of threading dislocations (10 8 ~10 10 pieces / cm 2The threading dislocations can cause a decrease in luminous efficiency and electrical leakage. Therefore, it is preferable that the n-type GaN layer 11 is laterally grown by the conventionally known ELO (Epitaxial Lateral Overgrowth) method, and has a low threading dislocation density region (not shown) in part. The region of the n-type GaN layer 11 that corresponds to the seed (seed crystal) used for lateral growth and the region (meeting portion) where the layers grown laterally from adjacent seeds meet are high dislocation density regions (10 8 ~10 10 pieces / cm 2 The lateral growth region between the two regions is a low dislocation density region (10 6 ~10 7 pieces / cm 2 (degree).

[0047] In the insulating film 12, three elongated rectangular openings 12a having the same planar shape are provided parallel to each other and at equal intervals on the low dislocation density region of the n-type GaN layer 11. The size of the openings 12a is selected as necessary, for example, (100 to 2000 nm) x (1 to 10 μm). On the n-type GaN layer 11 at the portion of each opening 12a, an island-like GaN layer 13 that is elongated in the longitudinal direction of the opening 12a is provided so as to extend on the insulating film 12 while being separated from each other. In this case, the GaN layer 13 has an octagonal pyramid shape extending in the longitudinal direction of the opening 12a. The GaN layer 13 may be undoped or n-type. 1A and 1B, a blue-emitting light-emitting layer 14 is provided in an island shape along the upper surface and side surface (slope) of the GaN layer 13 at the left-most opening 12a, a green-emitting light-emitting layer 15 is provided in an island shape along the upper surface and side surface (slope) of the GaN layer 13 at the central opening 12a, and a red-emitting light-emitting layer 16 is provided in an island shape along the upper surface and side surface (slope) of the GaN layer 13 at the right-most opening 12a. P-type GaN layers 17 are provided separately from each other so as to cover the light-emitting layers 14, 15, and 16, respectively. By appropriately selecting conditions such as temperature, growth rate, and pressure during crystal growth of the p-type GaN layer 17, the growth of the p-type GaN layer 17 in the lateral (horizontal) direction relative to the longitudinal (vertical) direction is promoted, and a part or all of the p-type GaN layer 17 above the upper surface of the GaN layer 13 and above the side surface (slope) of the GaN layer 13 is flattened. Therefore, the thickness of p-type GaN layer 17 above the top surface of GaN layer 13 is smaller than the thickness of p-type GaN layer 17 above the side surface (slope) of GaN layer 13. Note that a p-type AlGaN layer or the like is often inserted between light emitting layers 14, 15, 16 and p-type GaN layer 17, but illustration and description thereof are omitted.

[0048] The light-emitting layers 14, 15, and 16 may include, for example, In as a barrier layer. x Ga 1-x In as N-layer and well layer y Ga 1-y InN layers are stacked alternately. x Ga 1-x N / In y Ga 1-yIt has a multi - quantum well (MQW) structure (x < y, 0 ≤ x < 1, 0 ≤ y < 1). The In that constitutes the light - emitting layer 14 x Ga 1-x N / In y Ga 1-y The In composition ratios x and y of the N MQW structure are selected according to the emission wavelength of blue light. The In that constitutes the light - emitting layer 15 x Ga 1-x N / In y Ga 1-y The In composition ratios x and y of the N MQW structure are selected according to the emission wavelength of green light. The In that constitutes the light - emitting layer 16 x Ga 1-x N / In y Ga 1-y The In composition ratios x and y of the N MQW structure are selected according to the emission wavelength of red light. These In composition ratios x and y vary depending on the growth conditions of the In x Ga 1-x N layer and the In y Ga 1-y N layer, etc. The In composition of the light - emitting layers 14, 15, and 16 formed in a frustum - of - octagonal - pyramid shape following the frustum - of - octagonal - pyramid - shaped GaN layer 13 is larger in the part on the upper surface of the GaN layer 13 than in the part on the side surface of the GaN layer 13. This is because, compared with the InGaN growth on the polar C plane, in the InGaN growth on the non - polar and semi - polar planes, the In composition has the property of being lower at the same temperature. Therefore, the bandgap of the part of the light - emitting layers 14, 15, and 16 on the side surface of the GaN layer 13 is larger than the bandgap of the part on the upper surface of the GaN layer 13.

[0049] The n - type GaN layer 11, GaN layer 13, light - emitting layer 14, and p - type GaN layer 17 at the left - end opening 12a part form an AlGaInN - based LED structure B for blue light emission. The n - type GaN layer 11, GaN layer 13, light - emitting layer 15, and p - type GaN layer 17 at the central opening 12a part form an AlGaInN - based LED structure G for green light emission. The n - type GaN layer 11, GaN layer 13, light - emitting layer 16, and p - type GaN layer 17 at the right - end opening 12a part form an AlGaInN - based LED structure R for red light emission.

[0050] An insulating film 18 is provided so as to cover each p-type GaN layer 17. In the insulating film 18, a plurality of (four in this example) circular openings 18a are provided in a row at equal intervals on the center line in the longitudinal direction of each p-type GaN layer 17. The diameter of the openings 18a is selected as necessary, but is typically about the width (100 to 2000 nm) of the openings 18a. A plurality of (four in this example) p-side electrodes 19 are provided in a row, separated from one another, on the p-type GaN layer 17 along the center line in the longitudinal direction through each opening 18a at positions corresponding to the light-emitting layers 14, 15, and 16. In this case, in any of the blue-emitting AlGaInN-based LED structure B, the green-emitting AlGaInN-based LED structure G, and the red-emitting AlGaInN-based LED structure R, the N p Since = 1, the number of p-side electrodes 19 is N p ×N b ≧2, N p ×N g ≧2, N p ×N r ≧2, so N b ≧2, N g ≧2, N r ≧2, but in Figures 1A, 1B and 1C, N b , N g , N r are both selected as 4. The p-side electrode 19 is made of a multi-layered film such as an ITO / Ag / Ti / Au film. Here, Ag is used to increase the reflectance of light by the p-side electrode 19 when light is extracted from the n-type GaN layer 11 side of the micro LED chip 10. Here, the thicknesses of the ITO film, Ag film, Ti film, and Au film constituting the p-side electrode 19 are, for example, 50 nm, 100 nm, 20 nm, and 50 nm, respectively. A pair of elongated rectangular contact holes 12b are provided in a portion of the insulating film 12 away from the GaN layer 13 in a direction perpendicular to the extension direction of the GaN layer 13, parallel to the sides of the chip so as to sandwich the GaN layer 13, and two elongated rectangular n-side electrodes 20 are provided in contact with the n-type GaN layer 11 through the contact holes 12b. The n-side electrode 20 is made of a multi-layered film such as a Ti / Al / Ti / Ni / Au film.

[0051] The n-type GaN layer 11, the light emitting layers 14, 15, 16, and the p-type GaN layer 17 typically have a C-plane orientation. The resistivity of the n-type GaN layer 11 and the GaN layer 13 is, for example, about 0.01 Ωcm, but is not limited thereto. The resistivity of the light emitting layers 14, 15, 16 is, for example, about 0.1 to 0.3 Ωcm, but is not limited thereto. The resistivity of the p-type GaN layer 17 is, for example, about 1 to 3 Ωcm, but is not limited thereto. The thickness of the n-type GaN layer 11 is, for example, 1 to 5 μm, the thickness of the GaN layer 13 is, for example, 100 to 1500 nm, the thickness of the light emitting layers 14, 15, 16 is, for example, 30 to 100 nm, and the thickness of the part of the p-type GaN layer 17 above the upper surface of the GaN layer 13 is, for example, 100 to 200 nm, but is not limited thereto. The total thickness of n-type GaN layer 11, GaN layer 13, light emitting layer 14 and p-type GaN layer 15 is, for example, 1.2 to 6.8 μm, but is not limited to this.

[0052] [Operation of Micro LED chip] In this micro LED chip 10, blue light can be emitted by applying a forward bias between the p-electrode 19 and the n-electrode 20 in the blue light emitting AlGaInN based LED structure B, green light can be emitted by applying a forward bias between the p-electrode 19 and the n-electrode 20 in the green light emitting AlGaInN based LED structure G, and red light can be emitted by applying a forward bias between the p-electrode 19 and the n-electrode 20 in the red light emitting AlGaInN based LED structure R. In this case, the n-type GaN layer 11 and the p-type GaN layer 17 are separated by the insulating film 12 in the portion other than the opening 12a, so that the occurrence of leakage current during operation can be effectively suppressed. In addition, the thickness of the p-type GaN layer 17 having a high resistivity is smaller in the upper part of the upper surface of the GaN layer 13 than in the upper part of the side (slope) of the GaN layer 13, so that the current flowing between the p-side electrode 19 and the n-side electrode 20 mainly passes through the p-type GaN layer 17 in the upper part of the upper surface of the GaN layer 13, which has a lower resistance, and the current passing through the p-type GaN layer 17 in the upper part of the side of the GaN layer 13 is small. In addition, the In composition ratios x, y of the MQW structure of the light-emitting layers 14, 15, 16 are smaller in the upper part of the side of the GaN layer 13 than in the upper part of the upper surface of the GaN layer 13, so that the band gap of the light-emitting layers 14, 15, 16 is smaller in the upper part of the upper surface of the GaN layer 13 than in the upper part of the side of the GaN layer 13, but carriers (electrons, holes) tend to gather in the light-emitting layers 14, 15, 16 in the upper part of the upper surface of the GaN layer 13, which has a smaller band gap. Then, as a current flows between the p-side electrode 19 and the n-side electrode 20, light is emitted in the light-emitting layers 14, 15, and 16. Light is emitted mainly from the light-emitting layers 14, 15, and 16 in the upper portion of the upper surface of the GaN layer 13, and this light is extracted to the outside through the n-type GaN layer 11.

[0053] [Micro LED chip manufacturing method] In the following, two methods for manufacturing the micro LED chip will be described.

[0054] First, one example of a method for manufacturing a micro LED chip (manufacturing method 1) will be described.

[0055] First, as shown in FIG. 2A and FIG. 2B, an n-type GaN layer 11 is grown on a sapphire substrate 30 having a C-plane orientation, for example, by a metalorganic chemical vapor deposition (MOCVD) method. Here, FIG. 2A is a plan view, and FIG. 2B is a cross-sectional view. The growth of the n-type GaN layer 11 is performed, for example, as follows, but is not limited to this. That is, first, a GaN layer is epitaxially grown on the sapphire substrate 30 by a MOCVD method, and then a seed (not shown) is formed by patterning the GaN layer by a conventionally known method. Next, the n-type GaN layer 11 is grown by lateral growth from the seed using an ELO method based on a conventionally known MOCVD method. At this time, the growth is stopped at the point when the island-shaped n-type GaN layer 11 collides with the adjacent island-shaped n-type GaN layer 11. In some cases, the growth of the adjacent island-shaped n-type GaN layers 11 may continue even after the collision, or the growth can be stopped in a state where the n-type GaN layers 11 do not collide with each other by appropriately designing the position of the seed and the lateral growth distance. Next, an insulating film 12 such as a SiO2 film is formed on the n-type GaN layer 11 by chemical vapor deposition (CVD), sputtering, vacuum deposition, or the like, and then the insulating film 12 is patterned by a conventionally known method to form a long and narrow rectangular opening 12a in a portion where the blue light emitting AlGaInN based LED structure B is to be formed. The opening 12a is formed in a laterally grown region of the n-type GaN layer 11 that has a low threading dislocation density.

[0056] 3, the GaN layer 13 is grown in the shape of an octagonal pyramid island in each opening 12a by the ELO method. In this case, GaN is first selectively grown on the surface of the n-type GaN layer 11 exposed in the opening 12a of the insulating film 12, and then the GaN layer 13 is grown on the insulating film 12 by lateral growth. Next, In is grown on the island-shaped GaN layer 13 thus grown. x Ga 1-x N / In y Ga 1-yA light-emitting layer 14 having an N MQW structure is epitaxially grown. This blue-emitting light-emitting layer 14 can be grown by a conventionally known growth method. Usually, the In composition of the InGaN layer grown on the top surface (C-plane) of the GaN layer 13 is smaller than the In composition of the InGaN layer grown on the side surface (semi-polar plane). Subsequently, a p-type GaN layer 17 is epitaxially grown so as to cover the light-emitting layer 14. By adjusting the growth conditions such as pressure and temperature, it is possible to form the p-type GaN layer 17 in the upper part of the top surface of the GaN layer 13 to be thinner than the p-type GaN layer 17 in the upper part of the side surface of the GaN layer 13. The growth of the GaN layer 13, the light-emitting layer 14, and the p-type GaN layer 17 is performed continuously in an MOCVD furnace.

[0057] Next, as shown in FIG. 4, an insulating film 18 such as a SiO2 film is formed by, for example, vacuum deposition so as to cover the p-type GaN layer 17.

[0058] Next, as shown in FIG. 5, the insulating film 18 is patterned by a conventionally known method to form a long and narrow rectangular opening 12a in a portion where a green light emitting AlGaInN based LED structure G is to be formed.

[0059] Next, as shown in FIG. 6, on the n-type GaN layer 11 exposed in the newly formed opening 12a, a GaN layer 13 and an In layer are formed in the same manner as in the portion where the blue light emitting AlGaInN based LED structure B is to be formed. x Ga 1-x N / In y Ga 1-y A light emitting layer 15 having an N MQW structure and a p-type GaN layer 17 are grown in this order. The green light emitting layer 15 can be grown by a conventionally known growth method.

[0060] Next, as shown in FIG. 7, an insulating film 18 such as a SiO2 film is formed by, for example, a vacuum deposition method so as to cover the p-type GaN layer 17, and then the insulating film 18 is patterned by a conventionally known method to form a long and narrow rectangular opening 12a in a portion where a red light-emitting AlGaInN-based LED structure R is to be formed.

[0061] Next, as shown in FIG. 8, on the n-type GaN layer 11 exposed in the newly formed opening 12a, a GaN layer 13 and an In layer are formed in the same manner as in the portion where the blue light emitting AlGaInN based LED structure B is to be formed. x Ga 1-x N / In y Ga 1-y A light emitting layer 16 having a N MQW structure and a p-type GaN layer 17 are grown in sequence. The red light emitting layer 16 can be grown by a conventionally known growth method (e.g., Non-Patent Document 2). Subsequently, an insulating film 18 such as a SiO2 film is formed by, for example, a vacuum deposition method so as to cover the p-type GaN layer 17.

[0062] Next, as shown in FIG. 9, circular contact holes 18a are formed in the insulating film 18 on each of the blue-emitting AlGaInN-based LED structure B, the green-emitting AlGaInN-based LED structure G, and the red-emitting AlGaInN-based LED structure R, and the p-type GaN layer 17 is exposed inside the contact holes 18a.

[0063] Next, as shown in FIG. 10A and FIG. 10B, a p-side electrode 19 is formed to contact the p-type GaN layer 17 through the contact hole 18a. Here, FIG. 10A is a plan view, and FIG. 10B is a cross-sectional view. The p-side electrode 19 can be formed, for example, as follows. That is, an ITO film, an Ag film, a Ti film, and an Au film are sequentially formed on the entire surface of the substrate by, for example, a sputtering method or a vacuum deposition method, and then these ITO film, Ag film, Ti film, and Au film are patterned by etching or the like. Next, by patterning the insulating film 12 by a conventionally known method, two elongated rectangular contact holes 12b for the n-side electrode are formed in parallel to sandwich the entire blue light-emitting AlGaInN-based LED structure B, the green light-emitting AlGaInN-based LED structure G, and the red light-emitting AlGaInN-based LED structure R from both sides, and the n-type GaN layer 11 is exposed inside these contact holes 12b. Next, an elongated rectangular n-side electrode 20 is formed to contact the n-type GaN layer 11 through each of the contact holes 12b. One or more n-side electrodes 20 are sufficient, and two are formed in the example shown in FIGS. 10A and 10B.

[0064] 11A and 11B, an etching mask (not shown) for chip separation is formed, and then the sapphire substrate 30 is etched in a vertical direction by RIE using the etching mask until the sapphire substrate 30 is reached. In this way, separation grooves 31 are formed.

[0065] Next, as shown in Figure 12, a secondary substrate 40 is prepared on which a solder layer 41 is formed in the same arrangement pattern as the arrangement pattern of the p-side electrodes 19 and n-side electrodes 20 of a chip region selected from all chip regions (including the case where all chip regions are selected), and this secondary substrate 40 is superimposed so that the solder layer 41 corresponds to the p-side electrodes 19 and n-side electrodes 20 of the sapphire substrate 30 formed up to the separation groove 31 as shown in Figures 11A and 11B.

[0066] Next, as shown in FIG. 13, a laser beam is irradiated from the back side of the sapphire substrate 30 onto all or a selected part of the chip regions, causing peeling at the interface between the n-type GaN layer 11 in the chip region and the sapphire substrate 30 to separate the sapphire substrate 30 (laser lift-off). At the same time, the solder layer 41 in the portion corresponding to the chip region is melted by conduction of heat generated in the blue light-emitting AlGaInN-based LED structure B, the green light-emitting AlGaInN-based LED structure G, and the red light-emitting AlGaInN-based LED structure R during the laser beam irradiation. After that, the solder layer 41 cools and solidifies, and the sapphire substrate 30 is separated from the secondary substrate 40. When the laser beam is irradiated only onto the selected chip region from the back side of the sapphire substrate 30, the laser beam is irradiated using a predetermined mask (not shown) in which only the portion corresponding to the selected chip region is opened. Since the sapphire substrate 30 is transparent to visible light, it may be left as it is without peeling.

[0067] In the above manner, the micro LED chips 10 are manufactured in a state where they are transferred to predetermined positions on the secondary substrate 40, as shown in Fig. 14. Fig. 14 shows, as an example, a case where every third micro LED chip 10 is transferred.

[0068] Next, another example (manufacturing method 2) of the method for manufacturing a micro LED chip will be described.

[0069] 15A and 15B, an n-type GaN layer 11 is grown on a C-plane oriented sapphire substrate 30 in the same manner as in manufacturing method 1, and then an insulating film 12 is formed on the n-type GaN layer 11. The insulating film 12 is then patterned to form elongated rectangular openings 12a in the portions where the blue light emitting AlGaInN based LED structure B, the green light emitting AlGaInN based LED structure G, and the red light emitting AlGaInN based LED structure G are to be formed. Here, FIG. 15A is a plan view, and FIG. 15B is a cross-sectional view.

[0070] Next, as shown in FIG. 16, in the same manner as in manufacturing method 1, a GaN layer 13 is grown in the shape of a hexagonal pyramidal island in each of the openings 12a.

[0071] Next, as shown in FIG. 17, In was grown on the GaN layer 13 grown in the openings 12a. x Ga 1-x N / In y Ga 1-y The light emitting layer 14 having an N MQW structure is grown.

[0072] Next, as shown in FIG. 18, an insulating film 18 is formed so as to cover only the light emitting layer 14 in the portion where the blue light emitting AlGaInN based LED structure B is to be formed.

[0073] Next, as shown in FIG. 19, In ​​was deposited on the light-emitting layer 14 in the portion not covered with the insulating film 18. x Ga 1-x N / In y Ga 1-y A light emitting layer 15 having an N MQW structure is grown.

[0074] Next, as shown in FIG. 20, an insulating film 18 is formed so as to cover only the light emitting layer 15 in a portion where a green light emitting AlGaInN based LED structure G is to be formed.

[0075] Next, as shown in FIG. 21, In was deposited on the light-emitting layer 15 in the portion not covered with the insulating film 18. x Ga 1-x N / In y Ga 1-y A light emitting layer 16 having an N MQW structure is grown.

[0076] Next, as shown in FIG. 22, an insulating film 18 is formed so as to cover only the light emitting layer 16 in the portion where the red light emitting AlGaInN based LED structure R is to be formed, and then contact holes 18a are formed in the insulating film 18 on the light emitting layers 14, 15, and 16.

[0077] Next, as shown in FIG. 23, p-type GaN layers 17 are epitaxially grown on the light emitting layers 14, 15, and 16 inside each of the contact holes 18a, and then p-side electrodes 19 are formed on each of the p-type GaN layers 17 through the contact holes 18a.

[0078] Next, similarly to manufacturing method 1, the steps subsequent to superposing the secondary substrate 40 and the sapphire substrate 30 are carried out, and the micro LED chip 10 is manufactured in a state where it is transferred to the predetermined position of the secondary substrate 40.

[0079] Here, in the manufacturing method 2, in the green-emitting AlGaInN-based LED structure G, the green-emitting light-emitting layer 15 is grown on the blue-emitting light-emitting layer 14, and in the red-emitting AlGaInN-based LED structure R, the green-emitting light-emitting layer 15 is grown on the blue-emitting light-emitting layer 14, and the red-emitting light-emitting layer 16 is grown thereon. In this case, even if the light-emitting layer 14 exists in the green-emitting AlGaInN-based LED structure G, the light emission in the light-emitting layer 15, which is closest to the p-type GaN layer 17 serving as the hole injection layer and has a smaller band gap, becomes dominant, so that green light is emitted. Similarly, in the red-emitting AlGaInN-based LED structure R, even if the light-emitting layer 14 and the light-emitting layer 15 exist, the light emission in the light-emitting layer 16, which is closest to the p-type GaN layer 17 and has a smaller band gap, becomes dominant, so that red light is emitted.

[0080] As described above, according to the first embodiment, the light emitting layer 14 on the upper surface of the GaN layer 13 where light is mainly emitted is completely separated from the dry etching portion when forming the micro LED chip 10, and is not affected by etching damage. The current flowing between the p-side electrode 19 and the n-side electrode 20 also flows intensively in the light emitting layers 14, 15, and 16 on the upper surface of the GaN layer 13 due to the shape of the p-type GaN layer 17, so that the probability of electron-hole recombination in the light emitting layers 14, 15, and 16 on the upper surface of the GaN layer 13 can be kept high, thereby obtaining high light emission efficiency. In addition, the micro LED chip 10 can be easily and inexpensively manufactured using conventionally known techniques. In addition, the micro LED chip 10 has a blue-emitting AlGaInN-based LED structure B, a green-emitting AlGaInN-based LED structure G, and a red-emitting AlGaInN-based LED structure R on the n-type GaN layer 11, so that blue, green, and red light can be emitted from one chip. A high-performance micro LED display can be realized by using this high-performance micro LED chip 10, and high-performance XR glasses can be realized by using this micro LED display. In addition, this micro LED chip 10 has four p-side electrodes 19 for each of the blue-emitting AlGaInN-based LED structure B, the green-emitting AlGaInN-based LED structure G, and the red-emitting AlGaInN-based LED structure R, which can be controlled independently. Therefore, even if millions to tens of millions of micro LED chips are transferred and assembled together without inspecting each chip (total inspection), pixels can be repaired by isolating defective parts due to disconnection of wiring, and a high manufacturing yield of the micro LED display can be ensured.

[0081] Second embodiment [Micro LED chip transfer substrate] Fig. 24 is a cross-sectional view showing the micro LED chip transfer substrate 100. As shown in Fig. 24, the micro LED chip transfer substrate 100 has a large number of chip regions surrounded by separation grooves 31 in a two-dimensional array, as shown in Figs. 11A and 11B.

[0082] [Method of manufacturing the substrate for transferring micro LED chips] This micro LED chip transfer substrate 100 can be manufactured by carrying out the micro LED chip manufacturing method 1 or 2 according to the first embodiment up to the step of forming the separation grooves 31.

[0083] [How to use the Micro LED chip transfer substrate] In the same manner as in manufacturing method 1 of the first embodiment, the micro LED chip transfer substrate 100 is bonded to the secondary substrate 40 as shown in FIG. 25A, and then a laser beam is irradiated to transfer the micro LED chip 10 to a predetermined position on the secondary substrate 40 as shown in FIG. 25B.

[0084] According to the second embodiment, by using the micro LED chip transfer substrate 100, a large number of the micro LED chips 10 according to the first embodiment can be transferred to the secondary substrate 40 at once.

[0085] Third embodiment [Micro LED chip] 26A, 26B, and 26C show a micro LED chip 10 according to the third embodiment, in which 26A is a perspective view, 26B is a cross-sectional view taken along line BB in 26A, and 26C is a cross-sectional view taken along line CC in 26A. As shown in 26A, 26B, and 26C, in this micro LED chip 10, an insulating film 12 is provided on an n-type GaN layer 11. In this case, the insulating film 12 has a plurality of (four, for example) circular openings 12a arranged at equal intervals in a row at positions corresponding to the elongated rectangular openings 12a in the first embodiment. Then, island-shaped hexagonal truncated pyramidal GaN layers 13 are provided on the n-type GaN layer 11 at the portions of the openings 12a so as to extend on the SiO2 film 12. In the portion where the blue-emitting AlGaInN-based LED structure B is formed, the light-emitting layer 14 is provided in an island shape along the upper surface and side surface (slope) of the GaN layer 13, the p-type GaN layer 17 is provided to cover the light-emitting layer 14, an insulating film 18 is provided to cover the p-type GaN layer 17, and a p-side electrode 19 is provided on the p-type GaN layer 17 through a contact hole 18a provided in the insulating film 18. Similarly, in the portion where the green-emitting AlGaInN-based LED structure G is formed, the light-emitting layer 15 is provided in an island shape along the upper surface and side surface (slope) of the GaN layer 13, the p-type GaN layer 17 is provided to cover the light-emitting layer 15, an insulating film 18 is provided to cover the p-type GaN layer 17, and a p-side electrode 19 is provided on the p-type GaN layer 17 through a contact hole 18a provided in the insulating film 18. In the portion where the red-emitting AlGaInN-based LED structure R is formed, a light-emitting layer 16 is provided in an island shape along the upper surface and side surface (slope) of the GaN layer 13, a p-type GaN layer 17 is provided to cover the light-emitting layer 16, an insulating film 18 is provided to cover the p-type GaN layer 17, and a p-side electrode 19 is provided on the p-type GaN layer 17 through a contact hole 18a provided in the insulating film 18. In this case, the N b = 4, Green-emitting AlGaInN LED structure G g = 4, red-emitting AlGaInN LED structure R r= 4, and the number of p-side electrodes 19 is N p = 1, so N p ×N b ≧2, N p ×N g ≧2, N p ×N r ≧2 is satisfied. Other than the above, the micro LED chip 10 is similar to the micro LED chip 10 according to the first embodiment.

[0086] [Micro LED chip manufacturing method] First, as shown in FIG. 27A and FIG. 27B, in the same manner as in the manufacturing method 1 of the first embodiment, an n-type GaN layer 11 is grown on a sapphire substrate 30, an insulating film 12 is formed thereon, and then the insulating film 12 is patterned to form a circular opening 12a. Here, FIG. 27A is a plan view, and FIG. 27B is a cross-sectional view. Next, as shown in FIG. 28A and FIG. 28B, the process proceeds in the same manner as in the manufacturing method 1, and an island-shaped hexagonal truncated pyramidal GaN layer 13 is grown on the n-type GaN layer 11 in the opening 12a of the insulating film 12, and a blue-emitting AlGaInN-based LED structure B, a green-emitting AlGaInN-based LED structure G, and a red-emitting AlGaInN-based LED structure R are formed, and finally, the micro LED chip 10 is manufactured by transferring the structure to a secondary substrate 40. Here, FIG. 28A is a plan view, and FIG. 28B is a cross-sectional view.

[0087] According to the third embodiment, it is possible to obtain the same advantages as the first embodiment.

[0088] Fourth embodiment [Micro LED chip transfer substrate] Fig. 29 is a cross-sectional view showing the micro LED chip transfer substrate 100. As shown in Fig. 29, the micro LED chip transfer substrate 100 has a large number of chip regions surrounded by separation grooves 31 in a two-dimensional array as shown in Figs. 28A and 28B.

[0089] [Method of manufacturing the substrate for transferring micro LED chips] This micro LED chip transfer substrate 100 can be manufactured by carrying out the micro LED chip manufacturing method according to the third embodiment up to the step of forming the separation grooves 31.

[0090] [How to use the Micro LED chip transfer substrate] In the same manner as in the manufacturing method of the third embodiment, the micro LED chip transfer substrate 100 is bonded to the secondary substrate 40, and then the micro LED chip 10 is transferred to a predetermined position on the secondary substrate 40 by irradiating it with a laser beam.

[0091] According to the fourth embodiment, by using the micro LED chip transfer substrate 100, a large number of the micro LED chips 10 according to the third embodiment can be transferred to the secondary substrate 40 at once.

[0092] Fifth embodiment [XR Glasses] FIG. 30 shows the XR glasses according to the fifth embodiment. As shown in FIG. 30, in the XR glasses, a display unit 300 is attached to the inner surface of the part of the windshield units 201 and 202 for both eyes that faces the pupils of both eyes of the user when the user wears the XR glasses, on which a large number of micro LED chips 10 are mounted in a two-dimensional array. The windshield units 201 and 202 are generally made of glass or plastic, but may have a degree of a lens for myopia or hyperopia depending on the case. Since the distance between the display unit 300 and the pupils of both eyes of the user when the user wears the XR glasses is as short as a dozen or so mm, at least one lens (not shown) for adjusting the focal length is attached between the pupils and the light-emitting surface of the display unit 300, and is adjusted so that the focus is on each pixel at a distance that does not strain the eyes. The lens may be a convex lens or a Fresnel lens that covers the entire display unit 300, or a micro lens may be installed for each pixel. In addition, not only one lens but also a combination of multiple lenses may be used to configure an optical system. The display unit 300 is configured to be smaller than the windshield units 201, 202. The display unit 300 is connected to a drive circuit board 550 consisting of a Si-CMOSIC mounted on a printed circuit board 500 via a flexible printed circuit 400. The flexible printed circuit 400 and the printed circuit board 500 are mounted on a frame 203. The printed circuit board 500 is mounted in a state where it is wrapped around the ear hook portion of the frame 203. FIG. 31 shows an overall view of the display unit 300, the flexible printed circuit 400, and the printed circuit board 500.

[0093] Drive circuits 560 composed of CMOS circuits are provided in a two-dimensional array on the drive circuit board 550. In Fig. 31, one pixel drive circuit is composed of three adjacent drive circuits 560 shown by dashed lines on the drive circuit board 550. The size of the drive circuit 560 is selected as necessary and is not particularly limited, but is, for example, about 24 µm square.

[0094] The display unit 300 is shown in detail in FIG. 32A. FIG. 32B and FIG. 32C are cross-sectional views along the line BB and the line CC in FIG. 32A, respectively. As shown in FIG. 31, FIG. 32A, FIG. 32B and FIG. 32C, a large number of micro LED chips 10 having a blue light emitting AlGaInN based LED structure B, a green light emitting AlGaInN based LED structure G and a red light emitting AlGaInN based LED structure R are arranged in a two-dimensional array in the display unit 300. Four branch wirings 712 branched from a p-side wiring 711 connected to the drive circuit 560 of the drive circuit board 550 via the flexible printed circuit 400 per micro LED chip 10 are connected to the four p-side electrodes 19 of the blue light emitting AlGaInN based LED structure B, the green light emitting AlGaInN based LED structure G and the red light emitting AlGaInN based LED structure R, respectively. Although not shown, a thin film fuse is provided in the middle of the branch wiring 712, and when excessive current is applied due to a leak defect of the p-side electrode 19, the thin film fuse melts to disconnect the branch wiring 712. Two branch wirings 722 branched from an n-side wiring 721 connected to the drive circuit 560 of the drive circuit board 550 via the flexible printed circuit 400 are connected to the n-side electrodes 20 at both ends of the micro LED chip 10. A branch wiring 723 also branches from the n-side wiring 721 so as to connect the n-side electrodes 20 at both ends of the micro LED chip 10 to each other. In FIG. 32A, one pixel is formed by the portion surrounded by a dashed line. The size of one pixel is, for example, 4.2 μm×4.2 μm. This corresponds to a pixel density of 6000 ppi. If the chip size of the micro LED chip 10 is, for example, 1.6 μm×1.6 μm, the aperture ratio is approximately 85%. The power supply (battery) and control circuit of the display unit 300 and the drive circuit board 550 are provided in the ear hooks and windshields 201 and 202 of the frame 203 of the XR glasses. The mounting of the micro LED chip 10 on the display unit 300 can be easily performed using the third micro LED chip transfer substrate 100.

[0095] According to the fifth embodiment, the following advantages can be obtained. That is, the display unit 300 for XR glasses has a blue-emitting AlGaInN-based LED structure B, a green-emitting AlGaInN-based LED structure G, and a red-emitting AlGaInN-based LED structure R, and the micro LED chips 10 capable of emitting blue, green, and red light are arranged in a two-dimensional array. Therefore, the area of ​​the micro LED chip 10 in one pixel of the display unit 300 can be extremely small, and the aperture ratio of one pixel can be greatly increased. In addition, a pixel density of tens of thousands of PPI can be easily realized. Furthermore, the mounting of the micro LED chip 10 can be quickly and easily performed using the micro LED chip transfer substrate 100. In addition, in this XR glasses, since the printed circuit board 500 on which the driving circuit board 550 is mounted and the display unit 300 are connected to each other by the flexible printed circuit 400, it is sufficient to manufacture the array of the driving circuit 560 of the driving circuit board 550 at a lower density. As a result, high-performance XR glasses can be easily realized.

[0096] Sixth embodiment [XR Glasses] FIG. 33 shows XR glasses according to the sixth embodiment. As shown in FIG. 33, in the XR glasses, a light engine 600 is provided in a state of being wrapped around the ear hooks of the frame 303. FIG. 34 shows a development view of the light engine 600. As shown in FIG. 34, the light engine 600 has an LED array section 610 in which a large number of micro LED chips 10 are mounted in a two-dimensional array and a driving circuit board 550 made of a Si-CMOSIC mounted on a printed circuit board 500, which are connected by a flexible printed circuit 400. An optical waveguide (not shown) is provided from the light emitting section of the light engine 600 through the ear hooks of the frame 303 to the inner surfaces of the portions of the windshields 301 and 302 for both eyes that face the pupils of the user's eyes when the user wears the XR glasses. The light emitted from the micro LED chip 10 of the LED array section 610 of the light engine 600 enters one end of the optical waveguide through a lens (not shown), and is repeatedly totally reflected in the optical waveguide so that the light is emitted to the outside from the other end of the optical waveguide, and the other end of the optical waveguide constitutes the display section 300. In the LED array section 610, the micro LED chips 10 are connected by simple matrix wiring consisting of p-side wiring 711 and n-side wiring 721 arranged vertically and horizontally. The details of the LED array section 610 are shown in FIG. 35A. FIG. 35B and FIG. 32C are cross-sectional views along the line BB and the line CC in FIG. 35A, respectively. The micro LED chips 10 of the LED array section 610 can be easily mounted using the micro LED chip transfer substrate 100.

[0097] According to the sixth embodiment, since an optical waveguide is used in the display unit 300, there is no need to ensure an aperture ratio, and the light engine 600 can be advantageously made compact by arranging the micro LED chips 10 at a high density in the LED array unit 610.

[0098] Seventh embodiment [XR Glasses] The XR glasses according to the seventh embodiment differ from the XR glasses according to the sixth embodiment in the configuration of the light engine 600. Figure 36 shows the light engine 600 used in the XR glasses according to the seventh embodiment.

[0099] In the first to sixth embodiments, the sapphire substrate 30 used in the manufacture of the micro LED chip 10 is finally peeled off, but since the sapphire substrate 30 is transparent to visible light, it is possible to use it without peeling it off. Therefore, in the XR glass according to the seventh embodiment, after performing the steps before the step of forming the separation groove 31 on the sapphire substrate 30, the sapphire substrate 30 is polished from the back surface to be thinned. For example, a sapphire substrate 30 having a thickness of 400 μm is used, and the sapphire substrate 30 is thinned to a thickness of 100 μm or less, for example, 80 μm. Next, the sapphire substrate 30 is cut to a size including the required number of pixels, and as shown in FIG. 36, the sapphire substrate 30 of a predetermined size thus cut is bonded to a driving circuit substrate 550 consisting of a Si-CMOSIC mounted on a printed circuit substrate 500 as a secondary substrate. The printed circuit substrate 500 and the driving circuit substrate 550 are bonded with wires W. In this case, the LED array section 610 is bonded to the driving circuit substrate 550. The printed circuit board 500 is connected to a power supply and a control circuit via wiring 502 connected to a terminal 501. As in the sixth embodiment, light emitted from the micro LED chip 10 of the LED array unit 610 of the light engine 600 enters one end of the optical waveguide via a lens (not shown), and is repeatedly totally reflected within the optical waveguide before being emitted to the outside from the other end of the optical waveguide. The other end of the optical waveguide constitutes the display unit 300.

[0100] According to the seventh embodiment, it is possible to obtain advantages similar to those of the fifth and sixth embodiments.

[0101] Eighth embodiment [Laser diode chip] 37A and 37B show a laser diode (LD) chip 700 according to the eighth embodiment, with FIG. 37A being a plan view and FIG. 37B being a cross-sectional view taken along line BB in FIG. 37A. As shown in FIGS. 37A and 37B, the LD chip 700 has a rectangular planar shape as a whole, and has mesa-shaped blue-light-emitting AlGaInN-based LD structure B', green-light-emitting AlGaInN-based LD structure G', and red-light-emitting AlGaInN-based LD structure R' on an n-type GaN layer 701. The longitudinal direction of the LD chip 700 corresponds to the cavity length direction. On the n-type GaN layer 701, an n-type Al x Ga 1-x An N clad layer 702 (0≦x≦1) is provided. x Ga 1-x An insulating film 703 having a long and narrow rectangular opening 703a is provided on the N layer 702. The n-type Al x Ga 1-x On the N clad layer 702, a polygonal truncated pyramid of n-type Al y Ga 1-y In the blue-emitting AlGaInN-based LD structure B′, the n-type AlGaInN layer 704 (0≦y≦1) is disposed at the left end of the opening 703a in FIG. 37A and FIG. 37B. y Ga 1-y A blue light emitting active layer 705 is provided in an island shape along the upper surface and side surface (slope) of the N optical waveguide layer 704. In the green light emitting AlGaInN based LD structure G', the n-type AlGaInN layer in the central opening 703a in FIG. 37A and FIG. 37B y Ga 1-y An active layer 706 for emitting green light is provided in an island shape along the upper surface and side surface (slope) of the N-type optical waveguide layer 704. In the red-light emitting AlGaInN-based LD structure R', the n-type AlGaInN-based LD structure R' is formed in the portion of the opening 703a at the right end in FIG. 37A and FIG. 37B. y Ga 1-y Red light emitting active layers 707 are provided in islands along the top and side (slope) surfaces of the N-type optical waveguide layer 704. The active layers 705, 706, and 707 are configured similarly to the light emitting layers 14, 15, and 16, respectively. A p-type GaN optical waveguide layer 708 is provided so as to cover each of the active layers 705, 706, and 707. A p-type Al wGa 1-w An N-clad layer 709 (0 < w ≤ 1) and a p-type GaN contact layer 710 are sequentially provided. And a p-side electrode 711 is provided in ohmic contact on each p-type GaN contact layer 710. A portion of the n-type GaN layer 701 near the side parallel to the resonator length direction of the LD chip 700 is exposed, and an n-side electrode 712 is provided in ohmic contact on this exposed n-type GaN layer 701. Although not shown, end surface coatings are applied to both end surfaces perpendicular to the resonator length direction of the LD chip 700. That is, a high reflectivity (HR) film is coated on one end surface of the LD chip 700, and an antireflection (AR) film is coated on the other end surface. Note that the n-type GaN layer 701 may be provided on a C-plane sapphire substrate, an Si substrate, an n-type GaN substrate, etc. When the n-type GaN layer 701 is not provided on a substrate or when the n-type GaN layer 701 is provided on an n-type GaN substrate, the n-side electrode 712 may be provided on the back surface of the n-type GaN layer 701 or the back surface of the n-type GaN substrate.

[0102] [Operation of LD Chip] In this LD chip 700, by applying a forward bias between the p-side electrode 711 and the n-side electrode 712 in the blue light-emitting AlGaInN-based LD structure B', blue laser light can be emitted through the AR film. By applying a forward bias between the p-side electrode 711 and the n-side electrode 712 in the green light-emitting AlGaInN-based LD structure G', green laser light can be emitted. By applying a forward bias between the p-side electrode 711 and the n-side electrode 712 in the red light-emitting AlGaInN-based LD structure R', red laser light can be emitted. In this case, since the n-type GaN layer 702 and the p-type GaN optical waveguide layer 708 are separated by the insulating film 703 except for the opening 703a, the generation of leakage current during operation can be effectively suppressed. Also, the thickness of the p-type GaN optical waveguide layer 708 with a high resistivity is such that the portion above the upper surface of the n-type Al x Ga 1-x The N-clad layer 702 is larger above the upper surface. x Ga 1-xSince the upper part of the side (slope) of the N clad layer 702 is smaller than that of the p-side electrode 711 and the n-side electrode 712, the current flowing between the p-side electrode 711 and the n-side electrode 712 is caused by the n-type Al x Ga 1-x The light passes mainly through the p-type GaN optical waveguide layer 708 in the upper portion of the upper surface of the N cladding layer 702, and the n-type Al x Ga 1-x The current passing through the p-type GaN optical waveguide layer 708 in the upper portion of the side surface of the N cladding layer 702 is small. x Ga 1-x The n-type Al x Ga 1-x Since the upper part of the side of the N cladding layer 702 is smaller, the band gap of the active layers 705, 706, and 707 is n-type Al x Ga 1-x The upper part of the top surface of the N clad layer 702 is n-type Al x Ga 1-x The upper part of the side of the N clad layer 702 is smaller, but the carriers (electrons, holes) are smaller in the n-type Al x Ga 1-x Laser light tends to gather in the active layers 705, 706, and 707 in the upper portion of the upper surface of the N-clad layer 702. When a current flows between the p-side electrode 711 and the n-side electrode 712 in this manner, light is emitted in the active layers 705, 706, and 707, and the laser light is finally extracted to the outside through the AR film on the cavity end surface.

[0103] [LD chip manufacturing method] First, as shown in FIG. 38A, an n-type GaN layer 701 and an n-type Al layer 702 are formed on a substrate 800 in the same manner as in the manufacturing method 1 of the micro LED chip 10 according to the first embodiment. x Ga 1-x The N clad layer 702 is then grown, followed by the n-type Al x Ga 1-x An insulating film 703 is formed on the N clad layer 702, and openings 703a are formed in the insulating film 703. An n-type Al y Ga 1-yAn N-type optical waveguide layer 704 is grown, active layers 705, 706, and 707 are grown thereon, and a p-type GaN optical waveguide layer 708 is grown to cover the active layers 705, 706, and 707. The openings 703a in the insulating film 703 are formed at equal intervals within each unit of the blue-emitting AlGaInN-based LD structure B', the green-emitting AlGaInN-based LD structure G', and the red-emitting AlGaInN-based LD structure R', but the intervals between adjacent units are larger than that. The substrate 800 is, for example, a C-plane sapphire substrate, a Si substrate, or an n-type GaN substrate.

[0104] Next, as shown in FIG. 38B, p-type Al w Ga 1-w An N cladding layer 709 and a p-type GaN contact layer 710 are sequentially grown. If necessary, a p-type AlGaInN LD layer is formed on each of the blue-emitting AlGaInN LD structure B', the green-emitting AlGaInN LD structure G', and the red-emitting AlGaInN LD structure R'. w Ga 1-w By changing the refractive index (Al composition) and thickness of the N clad layer 709, w Ga 1-w An N-cladding layer 709 and a p-type GaN contact layer 710 may be grown.

[0105] Next, as shown in FIG. 38C, a p-side electrode 711 is formed on the p-type GaN contact layer 710 above the active layers 705, 706, and 707.

[0106] Next, as shown in FIG. 38D, a predetermined mask is used to etch n-type Al x Ga 1-x By performing etching until the N cladding layer 702 is reached, a blue-emitting AlGaInN-based LD structure B', a green-emitting AlGaInN-based LD structure G', and a red-emitting AlGaInN-based LD structure R' are formed separately from one another.

[0107] Next, as shown in FIG. 38E, the n-type AlGaInN-based LD structure B' for blue light emission, the AlGaInN-based LD structure G' for green light emission, and the AlGaInN-based LD structure R' for red light emission were removed from the n-type AlGaInN-based LD structure B' for green light emission and the n-type AlGaInN-based LD structure R' for red light emission. x Ga 1-x After the N cladding layer 702 and the upper portion of the n-type GaN layer 701 are etched by the RIE method or the like, an n-side electrode 712 is formed on the exposed n-type GaN layer 701 .

[0108] Next, the back surface of the substrate 800 is polished to reduce the thickness of the substrate 800 to about 100 μm or less.

[0109] Next, the substrate 800 on which the blue-emitting AlGaInN-based LD structure B', the green-emitting AlGaInN-based LD structure G', and the red-emitting AlGaInN-based LD structure R' are formed is cleaved by a conventionally known method to form laser bars, and then both end faces of the laser bars are coated with an AR film and an HR film, respectively, and the laser bars are then cut into chips.

[0110] In this manner, the desired LD chip 700 can be manufactured as shown in FIGS. 37A and 37B.

[0111] According to the eighth embodiment, one LD chip 700 has an AlGaInN-based LD structure B' for blue light emission, an AlGaInN-based LD structure G' for green light emission, and an AlGaInN-based LD structure R' for red light emission, so that one chip can emit blue, green, and red light. Moreover, each LD structure has a polygonal truncated n-type Al y Ga 1-y Since the light emitting layer is provided along the top and side surfaces of the N-optical waveguide layer 704, even if there are defects on the side surfaces of the LD chip caused by dry etching or the like, the defects have almost no effect on the light emission. As a result, high light emitting efficiency can be obtained even when miniaturized, and furthermore, since the structure is simple, it can be easily manufactured.

[0112] Although the embodiment of the present invention has been specifically described above, the present invention is not limited to the above-mentioned embodiment, and various modifications based on the technical concept of the present invention are possible.

[0113] For example, the numerical values, configurations, shapes, materials, methods, etc. given in the above-described embodiments are merely examples, and numerical values, configurations, shapes, materials, methods, etc. different from these may be used as necessary. [Explanation of symbols]

[0114] 10...vertical micro LED chip, 11...n-type GaN layer, 12...insulating film, 12a...opening, 13...GaN layer, 14, 15, 16...light-emitting layer, 17...p-type GaN layer, 18...insulating film, 18a...contact hole, 19...p-side electrode, 20...n-side electrode, 30...C-plane sapphire substrate, 40...secondary substrate, 41...solder layer, 701...n-type GaN layer, 702...n-type Al x Ga 1-x N clad layer, 703...insulating film, 703a...opening, 704...n-type Al y Ga 1-y N optical waveguide layer, 705, 706, 707...active layer, 708...p-type GaN optical waveguide layer, 709...p-type Al w Ga 1-w N cladding layer, 710...p-type GaN contact layer, 711...p-side electrode, 712...n-side electrode, B...blue-emitting AlGaInN-based LED structure, G...green-emitting AlGaInN-based LED structure, R...red-emitting AlGaInN-based LED structure, B'...blue-emitting AlGaInN-based LD structure, G'...green-emitting AlGaInN-based LD structure, R'...red-emitting AlGaInN-based LD structure

Claims

[Claim 1] n-type Al x G 1-x at least one blue-emitting AlGaInN-based laser diode structure, at least one green-emitting AlGaInN-based laser diode structure, and at least one red-emitting AlGaInN-based laser diode structure on an N layer (0≦x≦1); The above-mentioned blue-emitting AlGaInN-based laser diode structure, the above-mentioned green-emitting AlGaInN-based laser diode structure, and the above-mentioned red-emitting AlGaInN-based laser diode structure are The above n-type Al x G 1-x an insulating film having at least one rectangular opening provided on the N layer; The n-type Al in the opening of the insulating film x G 1-x A polygonal truncated pyramidal n-type Al layer is provided on the N layer. y G 1-y N layers (0≦y≦1); The polygonal truncated pyramidal n-type Al y G 1-y an active layer provided along the top and side surfaces of the N layer; A p-type Al layer is provided to cover the active layer. z G 1-z N layers (0≦z≦1); The p-type Al z G 1-z a p-side electrode provided on an upper surface of the N layer; The polygonal truncated pyramidal n-type Al y G 1-y The n-type Al in the portion where the N layer is not provided x G 1-x On the N layer or the above n-type Al x G 1-x and an n-side electrode provided on the back surface of the N layer.

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